/*
 * Copyright (c) 2007-2012, Oracle and/or its affiliates. All rights reserved.
 * ORACLE PROPRIETARY/CONFIDENTIAL. Use is subject to license terms.
 */
/*
 * Copyright 1999-2004 The Apache Software Foundation.
 *
 * Licensed under the Apache License, Version 2.0 (the "License");
 * you may not use this file except in compliance with the License.
 * You may obtain a copy of the License at
 *
 *     http://www.apache.org/licenses/LICENSE-2.0
 *
 * Unless required by applicable law or agreed to in writing, software
 * distributed under the License is distributed on an "AS IS" BASIS,
 * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
 * See the License for the specific language governing permissions and
 * limitations under the License.
 */
/*
 * $Id: HasPositionalPredChecker.java,v 1.1.2.1 2005/08/01 01:30:24 jeffsuttor Exp $
 */
package com.sun.org.apache.xpath.internal.axes;

import com.sun.org.apache.xpath.internal.Expression;
import com.sun.org.apache.xpath.internal.ExpressionOwner;
import com.sun.org.apache.xpath.internal.XPathVisitor;
import com.sun.org.apache.xpath.internal.functions.FuncLast;
import com.sun.org.apache.xpath.internal.functions.FuncPosition;
import com.sun.org.apache.xpath.internal.functions.Function;
import com.sun.org.apache.xpath.internal.objects.XNumber;
import com.sun.org.apache.xpath.internal.operations.Div;
import com.sun.org.apache.xpath.internal.operations.Minus;
import com.sun.org.apache.xpath.internal.operations.Mod;
import com.sun.org.apache.xpath.internal.operations.Mult;
import com.sun.org.apache.xpath.internal.operations.Plus;
import com.sun.org.apache.xpath.internal.operations.Quo;
import com.sun.org.apache.xpath.internal.operations.Variable;

public class HasPositionalPredChecker extends XPathVisitor {
    private boolean m_hasPositionalPred = false;
    private int m_predDepth = 0;

    /**
     * Process the LocPathIterator to see if it contains variables
     * or functions that may make it context dependent.
     * @param path LocPathIterator that is assumed to be absolute, but needs checking.
     * @return true if the path is confirmed to be absolute, false if it
     * may contain context dependencies.
     */
    public static boolean check(LocPathIterator path) {
        HasPositionalPredChecker hppc = new HasPositionalPredChecker();
        path.callVisitors(null, hppc);
        return hppc.m_hasPositionalPred;
    }

    /**
     * Visit a function.
     * @param owner The owner of the expression, to which the expression can
     *              be reset if rewriting takes place.
     * @param func The function reference object.
     * @return true if the sub expressions should be traversed.
     */
    public boolean visitFunction(ExpressionOwner owner, Function func) {
        if ((func instanceof FuncPosition) || (func instanceof FuncLast))
            m_hasPositionalPred = true;
        return true;
    }

    //      /**
    //       * Visit a variable reference.
    //       * @param owner The owner of the expression, to which the expression can
    //       *              be reset if rewriting takes place.
    //       * @param var The variable reference object.
    //       * @return true if the sub expressions should be traversed.
    //       */
    //      public boolean visitVariableRef(ExpressionOwner owner, Variable var)
    //      {
    //              m_hasPositionalPred = true;
    //              return true;
    //      }

    /**
     * Visit a predicate within a location path.  Note that there isn't a
     * proper unique component for predicates, and that the expression will
     * be called also for whatever type Expression is.
     *
     * @param owner The owner of the expression, to which the expression can
     *              be reset if rewriting takes place.
     * @param pred The predicate object.
     * @return true if the sub expressions should be traversed.
     */
    public boolean visitPredicate(ExpressionOwner owner, Expression pred) {
        m_predDepth++;

        if (m_predDepth == 1) {
            if ((pred instanceof Variable) || (pred instanceof XNumber) || (pred instanceof Div) || (pred instanceof Plus) || (pred instanceof Minus) || (pred instanceof Mod) || (pred instanceof Quo) || (pred instanceof Mult) || (pred instanceof com.sun.org.apache.xpath.internal.operations.Number) || (pred instanceof Function))
                m_hasPositionalPred = true;
            else
                pred.callVisitors(owner, this);
        }

        m_predDepth--;

        // Don't go have the caller go any further down the subtree.
        return false;
    }

}
